1. Field of the Invention
The present invention relates to a head protecting airbag system that deploys an airbag downward along the side of a vehicle body in a passenger compartment when the vehicle is involved in either a side collision or a rollover. In particular, the present invention relates to a head protecting airbag system that deploys an inflation section between an occupant's head and the vehicle body.
2. Description of the Related Art
In the recent trends, a head protecting airbag system is mounted to vehicles as a supplemental restraint system. The head protection airbag system has a curtain airbag that is deployed downward from a roof side rail when the vehicle is involved in a side collision or rollover. As one of such head protecting airbag systems, there has been proposed a head protecting airbag system designed to deploy the airbag between the head of the occupant seated on the seat and the side of the vehicle body in order to protect the occupant's head.
This type of head protecting airbag system is described in Japanese Patent Application Publication No. 2004-58848 (JP-A-2004-58848). In this head protecting airbag system, the airbag includes a gas supply path and a main inflation part disposed on the lower side of the gas supply path. The airbag is folded with the main inflation part rolled up toward the outer side in the width direction of the vehicle and with the gas supply path not rolled, but folded for the sake of easier deployment of the airbag upon gas supply. In addition, Japanese Patent No. 3520836 describes a head protecting airbag system including a head protecting area and an extended inflation area. The extended inflation area has an inflation section of a thickness smaller than the thickness of a cell in the head protecting area. The head protecting airbag system is designed to deploy the extended inflation area from the bottom end of the head protecting area to a position below a door beltline of the vehicle.
However, the direction in which the airbag is deployed tends to be affected by the manner in which the airbag is folded. Therefore, in order to immediately deploy the airbag in the vehicle longitudinal direction along the side of the passenger compartment, the lower end of the airbag has to reliably deploy inward towards the passenger compartment to an area below a side window opening.